Auxiliary switch for electromagnetically operated devices



p H. MATTHlAS- 2,297,423

AUXILIARY SWITCH FOR ELECTROMAGNETICALLY OPERATED DEVICES Filed Feb. 10, 1940 3 Sheets-Sheet 1 BY 204ml? ATTORNEY.

5 Sheets-Sheet 2 INVENTOR Z /m/ WWW/As A ORNEY.

L. H. MATTHIAS Filed Feb. 10, 1940 Sept. 29, 1942.

AUXILIARY SWITCH FOR ELECTROMAGNETICALLY OPERATED DEVICES I Sept. 29, 1942. 1 fims 2,297,423

AUXILIARY SWITCH FOR ELECTROMAGNETICALLY OPERATED DEVICES Filed Feb. 10, 1940 3 Sheets-Sheet 3 3% a I 14 6 I l l l l 14 5 I I I I I I I OPE/V 11/4 INVENTOR. ly/m fi/ WWW/As ATTORNEY.

Patented Sept. 29, 1942 UNITED STATES PATENT OFFICE AUXILIARY SWITCH FOR ELECTROMAG- NETICALLY OPERATED DEVICES 3 Claims.

This invention relates to an auxiliary switch for an electromagnetically operated device as disclosed in the application of Gustav O. Wilms and Albert J. Dawe for Electromagnetically operated devices, filed January 22, 1940, Serial Number 315,040 and assigned to the assignee of this application, which is the Allen-Bradley Company.

In the operation of an electromagnetic device where actuation of the movableelement of the electromagnet to the closed position is accomplished by energizing the magnetic circuit by means of A. C. or D. C. current and then maintaining the movable magnetic element in the closed position by means of residual magnetism derived from energization of the magnetic circuit during the operation of closing, the successful performance is largely dependent upon being able to de-energize the device at the proper instant. The object of this invention is to disclose a preferred arrangement for de-energizing the closing magnetizing circuit so as to obtain a more reliable magnetic lock for the electromagnetic device.

A further object of this invention is to secure a simple and satisfactory auxiliary switching device that is actuated by the movement of the movable member of an electromagnet and capable of obtaining and maintaining a very accurate relationship between the movement of the movable member of the electromagnet and the actuation of the switch.

A still further object of this invention is the provision of an auxiliary switching device actuated by the movable member of an electromag- 3 arrangement \and construction of parts as described below and on the attached drawings forming a part of this disclosure.

Referring to the drawings:

Figure 1 is a front view of an electromagnetically operated device with an attached auxiliary switch and shown in the unoperated position;

Figure 2 is a s de view of the device shown in Figure 1 with the auxiliary switch shown in section along lines 2--2 in Figure 1;

Figure 3 is a side view of the device shown in Figure l in the operated position and with the auxiliary switch shown in section along lines 33 in Figure 1;

Figure 4 is an enlarged partially sectioned view Application February 10, 1940, Serial No. 318,292

of the auxiliary switch taken along the lines 4-4 in Figure 2;

Figure 5 is a side view of an alternate form of the invention shown in the unoperated position with the auxiliary switch shown in a partially sectional view along the lines 5-5 in Figure 6; and

Figure 6 is a front view of the alternate form of the invention shown in Figure 5.

There are two specific disclosures of the invention shown that have proven to be highly satisfactory and are illustrative of the generic invention. Figures 1 and 6 show the two preferred forms and are explained in detail below.

Figures 1, 2, 3 and 4 show the form of auxiliary switch that has proven to be desirable when used with a solenoid type electromagnetic device in which the solenoid core is biased to the unoperated poistion essentially by gravity and it is undesirable to have the auxiliary switch effect the bias materially. This is particularly important on electromagnetically operated devices of comparatively small size. Figures 5 and 6 show the alternate form of auxiliary switch that is more suitable for uselon larger electromagnetically operated devices where the biasing action of the solenoid is sufficient to warrant some decrease due to the counter-biasing action of its auxiliary switch. Both forms of this device will be described simultaneously with reference to corresponding parts of the two types by separate, but related numerals-the second form differing from the first by the suffix one hundred i. e. first form 1, second form 101; or first form 2, second form 102, etc.

The electromagnetic device 2 or I02 and the auxiliary switch 6 or I 06 are rigidly mounted together by means of the mounting structure I or WI. The electromagnetic device 2 or I02 consists of a fieldpiece 3 or I03, armature 4 or I04 and coil 5 or I05. The auxiliary switch 6 or I06 consists of an insulating moulding I or I01 spaced from the mounting structure I or IN by means of a sheet of insulation 8 or I08 both being held rigidly in place by means of mounting screws 9 or I09. This switch has mounted therein a stationary contact terminal I0 or IIO with an attached tsationary contact II or III, another terminal I2 or H2 having attached thereto by means of a fiat metallic spring I4 or II4 a movable silver contact I3 or II3 arranged to engage or disengage the stationary silver contact II or III. The switch actuator I6 or H6 is pivotally mounted on base I or I01 by means of pivot I5 or H5 and arranged to engage or disengage the means of lock-nut I25.

flat spring I4 or II4 by means of the presser foot 28 or I28 to actuate the single-break auxiliary switch. x

The auxiliary switch actuating leverIG or H6 is coupled to the armature 4 or I04 by means of coupling device I1 or H1 50 that the contacts of the auxiliary switch are closed when the armature is in the unoperated posmion and open when in the operated position, The coupling device I1 or I I1 is soadjusted that the openingof the contacts occurs slightly before the pole faces 38 or I38 of the armature and fieldpiece engage. The detailed description thus far given relates to both forms disclosed and constitutes those parts of the deviceper se that have a common function. The coupling devices I1 or II1 are difierent in construction and operation and will be described in detail separately.

The couplingdevice I! used in the first form and shown in Figures 1, 2 and 3 consists of a coupling pin attached to a flat plate I8 that is rigidly mounted to the armature 4 by means of rivet I9. The auxiliary switch actuating lever I6 loosely engages the pin 20 by means of the shoulder of the hole 21 in the lever I6. A ball pointed adjusting screw 24 threaded in the lever I6 maintains a spaced'relation between th plate I8 and the lever I6 and is adjustable and can be locked by means of lock-nut 25. The lever I6 is maintained in the coupled position by means of coil spring 2| that fits in recess 26 on lever I6 and held in place by cup washer 22 and cotter pin 23. There is thus provided an extremely flexible coupling between the armature and the auxiliary switch actuating lever that introduces very little strain or friction on the armature, does not materially alter the bias of the armature, and yet, is capable of very accurate and reliable adjustment of the point of operation of the auxiliary switch.

In the second form shownin Figures 5 and 6 the auxiliary switch actuating lever II 6 has a heel I M that engages a biasing spring I39 that fits in the recess I40 of switch base I01. The lever is thus biased to the operated position of the electro-magnetic device and against the biasing action of the armature I04. The lever engages the armature by means of the'ball pointed adjusting screw I24 which is locked in place by There is thus provided a very simple coupling device between the armature and auxiliary switch actuating lever that introduces very little strain or friction on the armature and is capable of very accurate and reliable adjustment of the point of operation of the auxiliary switch.

The operation of the two forms shown in Figures 1 and 6 are similar. In the particular form disclosed, the fieldpiece 3 or I03 is constructed of laminations of steel having low retentivity and low coercive force and the armature 4 or I04 is constructed of laminations of steel having high retentivity and high coercive force. armature 4 or I04 in the disengaged position as shown, the silver contacts of the auxiliary switch 6 or I06 are in the closed position. In order to operate the electro-magnetic device 2 or I02 to With the of auxiliary switch 6 or I06 and conductor 32 or I32 to terminal 30 or I30. Thus a suiiicient A. C.

magnetizing force is developed in the coil 5 or I05 to cause the armature 4 or I 04 to move toward the closed position (specifically shown for form one in Figure 3) and to open the contacts of the auxiliary switch 6 or I06 substantially atthe time the armature 4 or I04 and fieldpiece '3 or I03 engage. If the energizing currentjs interrupted at a proper point on the A. C. power cycle, the residual flux in the magnetic circuit will be sufficient to hold the armature in the closed position against the bias of the armature. In the event that the residual flux is insufiicient to maintain the armature in the closed position, the magarmature and fieldpiece are about 0.010 inch.

cause the pole faces 38 or I38 of the armature 4' With an accurate and reliable adjustment of this magnitude a very satisfactory'and reliable closure of the armature is obtained.

In order to return the armature to the open position it is only necessary to energize the coil 5 or I05 with an A. C. magnetizing force just sufiicientto reduce the residual magnetism to a value insufiicient to maintain the armature in the closed position against its bias. This is accomplished as follows: with the close switch 3I or I3I open, a sufiicient source of A. C. power is connected to terminals 43 and 41 or I43 and I41 and the open switch 44 or I44 is operated completing a circuit from terminal 43 or I43, conductor 42 or I42, contacts of open switch 44 or I44,

conductor 45 or I45, conductor 34 or I34, coil 5 or I05, conductor 33 or I33 and conductor 48 or I48 to terminal 41 or I41.

The close switch 3I or I3I and open switch 44 or I 44 should bearranged so that both cannot be closed together. This can be accomplished by means of a mechanical interlock or other suitable arrangement.

The mode of operation of the electromagnetic device given above contains no reference to the theoretical explanation of its operation. The application of Gustav O. Wilms and Albert J. Dawe, referred to above, is directed to an electromagnetic device of the types shown in Figures 1 and 6 and adequately explains the theory of operation of the device and various modifications that can be incorporated therein without departing from the inventive thought. Reference to the Wilms and Dawe application will aid greatly in acquiring a proper appreciation of the importance and value of this invention in improv ing the operation of the Wilms and Dawe Electromagnetic device.

In the specific devices shown the armature moves from the open position to the closed position in an exceedingly short period of time. The device when operated on' 60 cycle A. C. current closes in approximatelyl cycle and the time interval for the armature to travel from the point of actuating the auxiliary switch to the closed position is approximately of a cycle. As the time required to extinguish an A. C. arc under proper conditions can be almost cycle, it is evident that the auxiliary switch actually interrupts the coil current after closure of the armature and fieldpiece. Any lag in motion of 'small gap and electrodes that cause the arc to persist, an effective time delay is obtained.

In other words the coil current is interrupted after closure of the armature witli the fieldpiece,

and such closure of the armature is at or substantially at zero value of the coil current.

The resultant eifect is a comparatively high value of magnetic flux in. the closed magnetic circuit of armature and fieldp-icce when the energizing current is cut off by the controlling switch. The electromagnet therefore remains in its closed position against the acting bias.

Electromagnetic devices of the type referred to herein are of compact and rugged construction and usually used in a wide variety of applications that demand reliable operation under adverse conditions. The electromagnetic device operates with tremendous force in a very short interval of time. It is, therefore, essential that the auxiliary switch be so arranged and constructed that objectionable rebound of parts be minimized, that wear of parts be proportioned so as to compensate in such manner that the operating characteristics are not impaired and that the structure be correspondingly compact and rugged.

While in accordance with the patent statutes I have disclosed details of two specific forms of my invention. and while certain of the claims are directed to the details of my preferred forms, it is to be understood that the principles disclosed are capable of much wider adaptation when used on electromagnetic devices generally. I desire, therefore, that the language of the claims be accorded the broadest reasonable construction, and that my invention shall be limited only by what is expressly stated therein and by the prior art.

I claim as my invention:

1. An electric switch for an electromagnet operable by alternating current, said electromagnet comprising a magnetic circuit including a fieldpiece, an energizing winding for said fieldpiece, and an armature biased from its closed position with the fieldpiece, said magnetic circuit with armature and fieldpiece closed capable of residual magnetism derived from energization of said winding by alternating current to providea holding force sufficient to maintain said armature closed against said bias; said electric switch comprising a movable member having a portion extending into the path of movement of said armature, aspring for urging said member into contact with said armature so as to cause said member to move to follow the movement of said armature, a pair of normally closed separable contacts electrically connected to said coil for interrupting current flowing therethrough, said contacts being positioned so as to be engaged and opened by said movable member during inward travel of said armature only after a point is reached near to the closed position of said armature, and adjustable means for adjustably fixing the point in the inward travel of the armature at which said contacts are engaged and separated.

2. An electric switch for an electromagnet operable by alternating current, said electromagnet comprising a magnetic circuit including a fieldpiece, an energizing winding for said fieldpiece, and an armature biased from its closed position with the field piece, said magnetic circuit with armature and ficldpiece closed capable of residual magnetism derived from energization of said winding by alternating current to provide a holding force suflicient to maintain said armature closed against said bias; said electric switch comprising a lever pivoted on a stationary support and having a follower arm extending into the path of movement of said armature and also having a contact actuating arm, a spring interposed between said stationary mounting and said lever for urging the follower arm of said lever toward said armature so as to cause said lever to follow the movement of said armature, a pair of normally closed separable contacts electrically connected to said coil for interrupting current flowing therethrough, said contacts be ing positioned so as to be engaged and opened by said contact actuating arm during inward travel of said armature only after a point is reached near to the closed position of said armature, and an adjusting finger interposed between' said follower arm and said armature for adjustably fixing the point in the inward travel of said armature at which said contacts are engaged and separated.

3. An electric switch for an electromagnet operable by alternating current, said electromagnet comprising a magnetic circuit includ ing a field piece, an energizing winding for said fieldpiece, and an armature biased from its closed position with the fielcpiece, said magnetic cir cuit with armature and fieldpiece closed capable of residual magnetism derived from energization of said winding by alternating current to provide a holding force sufficient to maintain said armature closed against said bias; said electric switch comprising a lever pivoted on a stationary support and having a follower arm extending into the path of movement of said. armature and also having a contact actuating arm, an extension rigidly secured to said armature, a spring interposed between said extension and said follower arm for urging said follower arm toward said armature so as to cause said lever to follow the movement of said armature, a pair of normally closed separable contacts electrically connected to said coil for interrupting current flowing therethrough, said contacts being positioned so as to be engaged and opened by said contact actuating arm during inward travel of said armature only after a point is reached near to the closed position of said armature, and an adjusting finger interposed between said follower arm and said armature for adjustably fixing the point in the inward travel of said armature at which said contacts are engaged and separated.

LYNN H. MATTHIAS. 

